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To: Frank A. Coluccio who wrote (6013)	11/18/1999 2:07:00 AM
From: Bernard Levy	Read Replies (1) \| Respond to of 12823

Hi Jack and Frank: While I can buy the emergence of common protocols and interfaces for the wired and wireless world, at the physical level, I view the development of a universal wireless system as impossible and in fact undesirable. Unlike in the fiber world, where bandwidth is plentiful, over the air bandwidth is a scarce commodity which needs to be exploited as efficiently as possible. The lower regions of the frequency spectrum (below 2GHz) allow flexible uses because of multipath propagation. Higher regions of the spectrum impose more constraints, such as line of sight and rain fade. However, as one goes up in the spectrum, BW becomes more plentiful. I view CDMA for PCS, VOFDM for MMDS, and current LMDS systems as systems which exploit very efficiently the constraints imposed by the part of the spectrum with which they work. New ideas, such as impulse radio, might ultimately carve new areas of application (presumably in the wireless LAN area). In particular, it is rather pleasing to see that the MMDS spectrum will be used at last very productively. It is rather amazing to see the ruthless efficiency of market forces in action, which essentially shifted a valuable asset, the MMDS spectrum, from an inefficient use (wireless cable) using an obsolete technology (analog TV signals) to a use in high-demand (2-way wireless data) using a highly optimized technology (in this respect both ADAP's system and CSCO's VOFDM should be viewed as big improvements). All of this occured in less than 3 years. Trying to push for a common wireless system would kill all the competitive tinkering which is needed to generate yet higher efficiencies. Best regards, Bernard Levy

To: Frank A. Coluccio who wrote (6013)	11/20/1999 4:54:00 PM
From: Frank A. Coluccio	Respond to of 12823

re: software radio and on the fly adaptation Thread, in post # 6013 which is uplink to this one I posited that wireless local loops would at some point be adaptable, on the fly, to a range of different parameters and standards. The future commodity status of users' terminal equipment (transceivers, expansion boards and other interface appliques) will almost guarantee this, IMO, when wireless proliferates to its ultimate stage of acceptance. The following link points to some interesting software radio approaches which leverage DSP techs now being explored that will bring some of this to fruition. Thanks to DH, for sending it to me. Frank ecpe.vt.edu